The present invention relates to ophthalmoscopes, and in particular, to a binocular indirect ophthalmoscope. Ophthalmoscopes are used by ophthalmologists to peer into the eye for eye examinations. Such ophthalmoscopes have an optical system that provides light typically through a hand held condenser lens and into the eye through a first optical path to enable the examination and provide an image from the eye, i.e., of the retina, back to the two eyes of the examiner via a second optical path. Hence, they are called “binocular indirect” ophthalmoscopes.
In conventional binocular indirect ophthalmoscopes, it is known to have a viewer module through which light is transmitted through a hand held condenser lens and to the eye that is being examined and also that provides an image from the illuminated eye back to the two eyes of the examining physician. In such known ophthalmoscopes, the viewer module can be moved from an in-use position wherein the viewer module is disposed in front of the face of the examining physician and an out-of-use position in which the viewer module is flipped upwardly above the eyes of the examiner. Further, it is known to provide these ophthalmoscopes with headbands to allow them to be worn on the head of the examiner for ease of use. One problem with such prior art ophthalmoscopes is providing a convenient and simple means to hold the viewer module in the in-use and out-of-use positions. In the past, various techniques have been utilized for this purpose including various mechanical mechanisms.
Further, the prior art ophthalmoscopes have typically utilized electrically operable circuits to provide for dimming of the intensity of the light provided from the illumination source to the eye being examined. Further, the illumination sources have typically been tungsten incandescent light sources. It is desirable to provide a simpler and more efficient means of both illuminating the eye being examined and for varying the intensity of the light provided to the eye being examined.
It is also desirable to provide a binocular indirect ophthalmoscope that it is easily adjusted once to the face of the examining physician thereby insuring a repeatable in-use position. Furthermore, it is desirable to provide such an ophthalmoscope that has a simple means for activating the illumination source when in the in-use position.